Plaster-board



UNITED STATES PATENT ,o1-"rica CHARLES B. BIRDSEY, 0F HINSDA'LE,

ILLINOIS, ASSIGN'OR, :BY MESNE T UNITED STATES GYPSUM COMPANY, OF CHICAGO, ELINOIS, A

ASSIGNMENTS, CORPORATION .Application filed July 29,

. of which the following is a description.

Mdy invention belongs to that general class of evicesknown as plaster board or the like, and relates particularly to an improvedboard which will be simple, substantial, durable, Satisfactory and efficient, and which may be economically and accurately manufactured. larly to a type of board in which the inclosed plaster, plaster Paris or plastic material is completel inclosed on one or on opposite edges, an in which the edges may be perfectly formed to conform to a definite specification as to size, the edge or edges being straight so that -meeting edges of adjacent boards ma be broughtclose together with but a smal crack or space between them.

To this end, my invention consists in the novel construction, arrangement and combination of parts herein shown and described and more particularly pointed out in the claims. y

In the drawings, wherein like reference characters indicate like or corresponding parts,

Figure 1 is a perspective view of a portion of the plaster board embodying theinvention;

Fig. 2 is a sectional view taken substantially on line22 of Fig. 1;

Fig. 3 is a somewhat similar ,view illustrating a step in the manufacture in producing a straight edge which will be accurately formed; and

Fig. 4 is a detailed kview illustrating how the covering sheet maybe scored .to facilitate folding or bending thereof.

Referring to the' drawings, 1 represents a body of suitable material, as for example plaster, plaster Paris or the equivalent suitable for the purpose, which may be handled in a plastic state and thereafter allowed to set or harden. The body is inclosed between the sheets 2 and 3 of suitable covering ma-y terial, and in this. connection it may be mentioned-that I, have found paper of the desired weight or thickness very -satisfactory for the purpose. In making the board a Specification of Letters atent.

The invention relates particu-lg manner, preferably fby allowing 'a portion material to flow between thel Patented lune 28, 19.21.

1918. Serial No. 247,244..

layer or layers of plastic material 1 forming the body of the board is placed on a sheet 2, which is preferably turned up at one or on opposite edges, and the covering sheet 3 placed over the plastic material. During the forming of the board the outer edge or edges of the sheet 2 are preferably turned as at 4 5. After the plastic material forming the body 1 isplaced onthe board and the covering sheet 3 placed over it, the extreme outer edge or edges 5 of Athe lower sheet are turned over the body so as to overlie the outer edges-6 of the sheet 3. Edge 5 is secured to the edge 6 in any suitable of the plastic two sheets during the y'manufacture of the board. Where plastic material of the kind described is used as the body 1, this will s,

sheet 8 at this -time tends topartake of the stiffness of the body. That is to say, pressure applied to the edge of-the sheet 3, for example as at the point 10 (see Figs. 2 and 3), will not only vhave the normal stiffness of the paper to push against. but owing to the adhering of the paper to the body 1 there will be but slight tendency for the paper to crumple up, as it will be held down by the body. The result therefore is that the edge of the sheet 3 at the point 10 acts substantially as a straight edge over which thevend 5 may be bent. Ordinarily it is preferred to score the sheet 2" as at 8 and 9 to facilitate the bending to form the edge 4 of the board and the top of the overlying portion 5, Any material that seeps through as at 10, while ordinarily slight, is spread over the edge 6 to the under' sheet by the bending down of the edge 5 of the sheet 2, thus securing in the` manufacture, opposite ed es of the continuous board are formed simi ar to that between the scorings 8 at each side of the edge 5 to edge 6. Ordinarily illustrated in the drawings. The distance being possibly aov "indicated by the numeral board may be accuratelv gaged as desired. This is also true of the cover sheet 3. Consequently, when the part 5 is turned over the edge 4 is formed accurately in av predetermined manner without any rolling or curve, for example, without any half round` effect. In turning downI edge 5 there may be a possibility of the end (being pushed in a little at the free edge, but ordinarily this is insufiicient to affect the gaging and vary the straight edge action.

, In Fig. 2 I have illustrated in dotted lines the edge turned slightly downward, this an exaggerated instance. However, this takes effect practically at the last step of the manufacture, and eventhen the downward depressing of end GgA is hardly sufficient to straight edge action. In this connection,

should end 6 be turned down as shown and 6', there 1s no weakening of the board, as almost the 'entire body is present exceptl possibly at the extreme edge of the sheet 3, at which polnt a slight reduction in the amount of material would not be harmful.V In any event, the

board would be stiff owing to the full amount of material between the4 edge 5' and the bottom. This might be perhaps better understood by stating that a board is not easily broken at the extreme edge, but may at times be easily broken farther in from the edge. vIn the present case, however, assuming that in manufacture end 6 did occaslonally become depressed, this would be immaterial as the board to all practical vpurposes would` not be weakened.

By manufacturing a board as described the resulting product is produced with a straight, smooth edge and at a perfect angle, the board being uniform in width throughout its length. The completed product has numerous advantages, among which may beenumerated increased strength and durability, and an improved appearance. If any of the plastic sealing material flows beyond the free edge 5, the same is spaced back from the edge of the board so that all of the extreme edges of the board are of pleasing appearance and perfectly true, there being no protruding plastic material on the edge. The extending of the cover sheet 3 to the 'extreme edge of the board gives the full strength of the sheet from edge to edge. This is true for both cover sheets, and in case of any strain from contraction or expansion of the board, or sheets in manufacture or otherwise, the effect is uniform throughout the faces of the board. Should it happen that from-lack of sufficient plastic material at 7, part 5 shouldgnot adhere perfectly to sheet 3, the appearance and strength of the board and its utllity would not in any way be impaired. In fact, side part 4 of sheet 2 would be maintained in place by its affect. the gaging or.

extending to adjacent vof the body,

adhering to the other face of the body and additional expense 1s entirely obviated.

Having thus described my invention, it

is obvious that variousimmaterial modifi.

cations may be made in the same without departing from .the spirit of `my invention; hence I do not wish to be understood as limiting myself to the exact form, construction, arrangement and combination of parts herein shown and described or uses mentioned.

vWhat I claim as new and desire to secure by Letters Patent is 1. A'plaster board`comprising a body, a'

relatively stiff covering sheet of fibrous material adhering to .one face of the body and extending to adjacent one edge of the body,4

and a second covering sheet adhering to the other'face of the body and having an extension'at one side folded over to inclose the edge ofthe body and overlie a portion of the body andthe edge portion of the first covering sheet.

2. A plaster board comprising a body, a

relatively stiffl covering sheet of fibrous maface of the body and one edge of the body, and a second similarly relatively stiff covering sheet adhering to the other face of the body and having an extension at one Side terial adhering to one folded over to inclose the edge of the body.

and overlie a portion of the body and the edge portion of the first covering sheet.

plaster board comprising a body, a relatively stiff imperforate coverlng sheet of fibrous material adhering to one face of the body and extending to adjacent one edge andra second covering sheet having an extension at one side foldedover to inclose the edge of the body and overlie a portion of the body and the edge portion of the first covering sheet.

4. A plaster board comprising a body, an imperforate covering sheet adheringrto one face of the body and extending to adjacent one edge ofthe body, and a second covering sheet adhering to the other face of the bod and having an extension at one side folde over to inclose the edge of the body and overlie a portion of the body and the edge portion of the first covering sheet.

5. A plaster board comprising a body, an imperforate covering sheet adhering to one face ofthe body and extending to adjacent one edge of the body, and a second imperiorate covering sheet adhering to the otherA fastened on the outer face of the body and having an extension at e tension at one side folded over to inclose the one side folded over to inclose vthe edge of edge of the body and overlie a, portion of the body and overlie a portion of the body the body and the edge portion of the first 12 and the edge portion of the first covering covering sheet. e 5 sheet. e nvtestimony whereof, I have hereunto 6. A plaster board comprising a, body, a signed my neme inthe presence of two Sublatively stiff ilmyelelrforate coverizlfig shet lof scribing witnesses.

rous materia a erin to one ace o t e body andextending to mgijacent one ed e of CHARLES R' B IRD SEY' 10 th body, and a second relatively sti im- Witnesses: perforate covering sheet Aadhering to ,the Roy W. HILL,

L other face' of the body and having an qx- CHARLES I. COBB. 

